/*
 * Ricoh RS5C313 RTC device/driver
 *  Copyright (C) 2007 Nobuhiro Iwamatsu
 *
 *  2005-09-19 modifed by kogiidena
 *
 * Based on the old drivers/char/rs5c313_rtc.c  by:
 *  Copyright (C) 2000 Philipp Rumpf <prumpf@tux.org>
 *  Copyright (C) 1999 Tetsuya Okada & Niibe Yutaka
 *
 * Based on code written by Paul Gortmaker.
 *  Copyright (C) 1996 Paul Gortmaker
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Based on other minimal char device drivers, like Alan's
 * watchdog, Ted's random, etc. etc.
 *
 *	1.07	Paul Gortmaker.
 *	1.08	Miquel van Smoorenburg: disallow certain things on the
 *		DEC Alpha as the CMOS clock is also used for other things.
 *	1.09	Nikita Schmidt: epoch support and some Alpha cleanup.
 *	1.09a	Pete Zaitcev: Sun SPARC
 *	1.09b	Jeff Garzik: Modularize, init cleanup
 *	1.09c	Jeff Garzik: SMP cleanup
 *	1.10    Paul Barton-Davis: add support for async I/O
 *	1.10a	Andrea Arcangeli: Alpha updates
 *	1.10b	Andrew Morton: SMP lock fix
 *	1.10c	Cesar Barros: SMP locking fixes and cleanup
 *	1.10d	Paul Gortmaker: delete paranoia check in rtc_exit
 *	1.10e	Maciej W. Rozycki: Handle DECstation's year weirdness.
 *      1.11    Takashi Iwai: Kernel access functions
 *			      rtc_register/rtc_unregister/rtc_control
 *      1.11a   Daniele Bellucci: Audit create_proc_read_entry in rtc_init
 *	1.12	Venkatesh Pallipadi: Hooks for emulating rtc on HPET base-timer
 *		CONFIG_HPET_EMULATE_RTC
 *	1.13	Nobuhiro Iwamatsu: Updata driver.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/err.h>
#include <linux/rtc.h>
#include <linux/platform_device.h>
#include <linux/bcd.h>
#include <linux/delay.h>
#include <linux/io.h>

#define DRV_NAME	"rs5c313"

#ifdef CONFIG_SH_LANDISK
/*****************************************************/
/* LANDISK dependence part of RS5C313                */
/*****************************************************/

#define SCSMR1		0xFFE00000
#define SCSCR1		0xFFE00008
#define SCSMR1_CA	0x80
#define SCSCR1_CKE	0x03
#define SCSPTR1		0xFFE0001C
#define SCSPTR1_EIO	0x80
#define SCSPTR1_SPB1IO	0x08
#define SCSPTR1_SPB1DT	0x04
#define SCSPTR1_SPB0IO	0x02
#define SCSPTR1_SPB0DT	0x01

#define SDA_OEN		SCSPTR1_SPB1IO
#define SDA		SCSPTR1_SPB1DT
#define SCL_OEN		SCSPTR1_SPB0IO
#define SCL		SCSPTR1_SPB0DT

/* RICOH RS5C313 CE port */
#define RS5C313_CE	0xB0000003

/* RICOH RS5C313 CE port bit */
#define RS5C313_CE_RTCCE	0x02

/* SCSPTR1 data */
unsigned char scsptr1_data;

#define RS5C313_CEENABLE    __raw_writeb(RS5C313_CE_RTCCE, RS5C313_CE);
#define RS5C313_CEDISABLE   __raw_writeb(0x00, RS5C313_CE)
#define RS5C313_MISCOP      __raw_writeb(0x02, 0xB0000008)

static void rs5c313_init_port(void)
{
	/* Set SCK as I/O port and Initialize SCSPTR1 data & I/O port. */
	__raw_writeb(__raw_readb(SCSMR1) & ~SCSMR1_CA, SCSMR1);
	__raw_writeb(__raw_readb(SCSCR1) & ~SCSCR1_CKE, SCSCR1);

	/* And Initialize SCL for RS5C313 clock */
	scsptr1_data = __raw_readb(SCSPTR1) | SCL;	/* SCL:H */
	__raw_writeb(scsptr1_data, SCSPTR1);
	scsptr1_data = __raw_readb(SCSPTR1) | SCL_OEN;	/* SCL output enable */
	__raw_writeb(scsptr1_data, SCSPTR1);
	RS5C313_CEDISABLE;	/* CE:L */
}

static void rs5c313_write_data(unsigned char data)
{
	int i;

	for (i = 0; i < 8; i++) {
		/* SDA:Write Data */
		scsptr1_data = (scsptr1_data & ~SDA) |
				((((0x80 >> i) & data) >> (7 - i)) << 2);
		__raw_writeb(scsptr1_data, SCSPTR1);
		if (i == 0) {
			scsptr1_data |= SDA_OEN;	/* SDA:output enable */
			__raw_writeb(scsptr1_data, SCSPTR1);
		}
		ndelay(700);
		scsptr1_data &= ~SCL;	/* SCL:L */
		__raw_writeb(scsptr1_data, SCSPTR1);
		ndelay(700);
		scsptr1_data |= SCL;	/* SCL:H */
		__raw_writeb(scsptr1_data, SCSPTR1);
	}

	scsptr1_data &= ~SDA_OEN;	/* SDA:output disable */
	__raw_writeb(scsptr1_data, SCSPTR1);
}

static unsigned char rs5c313_read_data(void)
{
	int i;
	unsigned char data = 0;

	for (i = 0; i < 8; i++) {
		ndelay(700);
		/* SDA:Read Data */
		data |= ((__raw_readb(SCSPTR1) & SDA) >> 2) << (7 - i);
		scsptr1_data &= ~SCL;	/* SCL:L */
		__raw_writeb(scsptr1_data, SCSPTR1);
		ndelay(700);
		scsptr1_data |= SCL;	/* SCL:H */
		__raw_writeb(scsptr1_data, SCSPTR1);
	}
	return data & 0x0F;
}

#endif /* CONFIG_SH_LANDISK */

/*****************************************************/
/* machine independence part of RS5C313              */
/*****************************************************/

/* RICOH RS5C313 address */
#define RS5C313_ADDR_SEC	0x00
#define RS5C313_ADDR_SEC10	0x01
#define RS5C313_ADDR_MIN	0x02
#define RS5C313_ADDR_MIN10	0x03
#define RS5C313_ADDR_HOUR	0x04
#define RS5C313_ADDR_HOUR10	0x05
#define RS5C313_ADDR_WEEK	0x06
#define RS5C313_ADDR_INTINTVREG	0x07
#define RS5C313_ADDR_DAY	0x08
#define RS5C313_ADDR_DAY10	0x09
#define RS5C313_ADDR_MON	0x0A
#define RS5C313_ADDR_MON10	0x0B
#define RS5C313_ADDR_YEAR	0x0C
#define RS5C313_ADDR_YEAR10	0x0D
#define RS5C313_ADDR_CNTREG	0x0E
#define RS5C313_ADDR_TESTREG	0x0F

/* RICOH RS5C313 control register */
#define RS5C313_CNTREG_ADJ_BSY	0x01
#define RS5C313_CNTREG_WTEN_XSTP	0x02
#define RS5C313_CNTREG_12_24	0x04
#define RS5C313_CNTREG_CTFG	0x08

/* RICOH RS5C313 test register */
#define RS5C313_TESTREG_TEST	0x01

/* RICOH RS5C313 control bit */
#define RS5C313_CNTBIT_READ	0x40
#define RS5C313_CNTBIT_AD	0x20
#define RS5C313_CNTBIT_DT	0x10

static unsigned char rs5c313_read_reg(unsigned char addr)
{

	rs5c313_write_data(addr | RS5C313_CNTBIT_READ | RS5C313_CNTBIT_AD);
	return rs5c313_read_data();
}

static void rs5c313_write_reg(unsigned char addr, unsigned char data)
{
	data &= 0x0f;
	rs5c313_write_data(addr | RS5C313_CNTBIT_AD);
	rs5c313_write_data(data | RS5C313_CNTBIT_DT);
	return;
}

static inline unsigned char rs5c313_read_cntreg(void)
{
	return rs5c313_read_reg(RS5C313_ADDR_CNTREG);
}

static inline void rs5c313_write_cntreg(unsigned char data)
{
	rs5c313_write_reg(RS5C313_ADDR_CNTREG, data);
}

static inline void rs5c313_write_intintvreg(unsigned char data)
{
	rs5c313_write_reg(RS5C313_ADDR_INTINTVREG, data);
}

static int rs5c313_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
	int data;
	int cnt;

	cnt = 0;
	while (1) {
		RS5C313_CEENABLE;	/* CE:H */

		/* Initialize control reg. 24 hour */
		rs5c313_write_cntreg(0x04);

		if (!(rs5c313_read_cntreg() & RS5C313_CNTREG_ADJ_BSY))
			break;

		RS5C313_CEDISABLE;
		ndelay(700);	/* CE:L */

		if (cnt++ > 100) {
			dev_err(dev, "%s: timeout error\n", __func__);
			return -EIO;
		}
	}

	data = rs5c313_read_reg(RS5C313_ADDR_SEC);
	data |= (rs5c313_read_reg(RS5C313_ADDR_SEC10) << 4);
	tm->tm_sec = bcd2bin(data);

	data = rs5c313_read_reg(RS5C313_ADDR_MIN);
	data |= (rs5c313_read_reg(RS5C313_ADDR_MIN10) << 4);
	tm->tm_min = bcd2bin(data);

	data = rs5c313_read_reg(RS5C313_ADDR_HOUR);
	data |= (rs5c313_read_reg(RS5C313_ADDR_HOUR10) << 4);
	tm->tm_hour = bcd2bin(data);

	data = rs5c313_read_reg(RS5C313_ADDR_DAY);
	data |= (rs5c313_read_reg(RS5C313_ADDR_DAY10) << 4);
	tm->tm_mday = bcd2bin(data);

	data = rs5c313_read_reg(RS5C313_ADDR_MON);
	data |= (rs5c313_read_reg(RS5C313_ADDR_MON10) << 4);
	tm->tm_mon = bcd2bin(data) - 1;

	data = rs5c313_read_reg(RS5C313_ADDR_YEAR);
	data |= (rs5c313_read_reg(RS5C313_ADDR_YEAR10) << 4);
	tm->tm_year = bcd2bin(data);

	if (tm->tm_year < 70)
		tm->tm_year += 100;

	data = rs5c313_read_reg(RS5C313_ADDR_WEEK);
	tm->tm_wday = bcd2bin(data);

	RS5C313_CEDISABLE;
	ndelay(700);		/* CE:L */

	return 0;
}

static int rs5c313_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
	int data;
	int cnt;

	cnt = 0;
	/* busy check. */
	while (1) {
		RS5C313_CEENABLE;	/* CE:H */

		/* Initiatlize control reg. 24 hour */
		rs5c313_write_cntreg(0x04);

		if (!(rs5c313_read_cntreg() & RS5C313_CNTREG_ADJ_BSY))
			break;
		RS5C313_MISCOP;
		RS5C313_CEDISABLE;
		ndelay(700);	/* CE:L */

		if (cnt++ > 100) {
			dev_err(dev, "%s: timeout error\n", __func__);
			return -EIO;
		}
	}

	data = bin2bcd(tm->tm_sec);
	rs5c313_write_reg(RS5C313_ADDR_SEC, data);
	rs5c313_write_reg(RS5C313_ADDR_SEC10, (data >> 4));

	data = bin2bcd(tm->tm_min);
	rs5c313_write_reg(RS5C313_ADDR_MIN, data);
	rs5c313_write_reg(RS5C313_ADDR_MIN10, (data >> 4));

	data = bin2bcd(tm->tm_hour);
	rs5c313_write_reg(RS5C313_ADDR_HOUR, data);
	rs5c313_write_reg(RS5C313_ADDR_HOUR10, (data >> 4));

	data = bin2bcd(tm->tm_mday);
	rs5c313_write_reg(RS5C313_ADDR_DAY, data);
	rs5c313_write_reg(RS5C313_ADDR_DAY10, (data >> 4));

	data = bin2bcd(tm->tm_mon + 1);
	rs5c313_write_reg(RS5C313_ADDR_MON, data);
	rs5c313_write_reg(RS5C313_ADDR_MON10, (data >> 4));

	data = bin2bcd(tm->tm_year % 100);
	rs5c313_write_reg(RS5C313_ADDR_YEAR, data);
	rs5c313_write_reg(RS5C313_ADDR_YEAR10, (data >> 4));

	data = bin2bcd(tm->tm_wday);
	rs5c313_write_reg(RS5C313_ADDR_WEEK, data);

	RS5C313_CEDISABLE;	/* CE:H */
	ndelay(700);

	return 0;
}

static void rs5c313_check_xstp_bit(void)
{
	struct rtc_time tm;
	int cnt;

	RS5C313_CEENABLE;	/* CE:H */
	if (rs5c313_read_cntreg() & RS5C313_CNTREG_WTEN_XSTP) {
		/* INT interval reg. OFF */
		rs5c313_write_intintvreg(0x00);
		/* Initialize control reg. 24 hour & adjust */
		rs5c313_write_cntreg(0x07);

		/* busy check. */
		for (cnt = 0; cnt < 100; cnt++) {
			if (!(rs5c313_read_cntreg() & RS5C313_CNTREG_ADJ_BSY))
				break;
			RS5C313_MISCOP;
		}

		memset(&tm, 0, sizeof(struct rtc_time));
		tm.tm_mday	= 1;
		tm.tm_mon	= 1 - 1;
		tm.tm_year	= 2000 - 1900;

		rs5c313_rtc_set_time(NULL, &tm);
		pr_err("invalid value, resetting to 1 Jan 2000\n");
	}
	RS5C313_CEDISABLE;
	ndelay(700);		/* CE:L */
}

static const struct rtc_class_ops rs5c313_rtc_ops = {
	.read_time = rs5c313_rtc_read_time,
	.set_time = rs5c313_rtc_set_time,
};

static int rs5c313_rtc_probe(struct platform_device *pdev)
{
	struct rtc_device *rtc = devm_rtc_device_register(&pdev->dev, "rs5c313",
				&rs5c313_rtc_ops, THIS_MODULE);

	if (IS_ERR(rtc))
		return PTR_ERR(rtc);

	platform_set_drvdata(pdev, rtc);

	return 0;
}

static struct platform_driver rs5c313_rtc_platform_driver = {
	.driver         = {
		.name   = DRV_NAME,
	},
	.probe	= rs5c313_rtc_probe,
};

static int __init rs5c313_rtc_init(void)
{
	int err;

	err = platform_driver_register(&rs5c313_rtc_platform_driver);
	if (err)
		return err;

	rs5c313_init_port();
	rs5c313_check_xstp_bit();

	return 0;
}

static void __exit rs5c313_rtc_exit(void)
{
	platform_driver_unregister(&rs5c313_rtc_platform_driver);
}

module_init(rs5c313_rtc_init);
module_exit(rs5c313_rtc_exit);

MODULE_AUTHOR("kogiidena , Nobuhiro Iwamatsu <iwamatsu@nigauri.org>");
MODULE_DESCRIPTION("Ricoh RS5C313 RTC device driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:" DRV_NAME);